Systems and methods for packet routing

ABSTRACT

Systems and methods to route packets of information within an integrated circuit, across one or more boards, racks, blades, and/or chassis, and/or across a connected network of packet processing engines include various modes of operation. Packets are routed to their destination, for example an individual packet processing engine. The packets of information include address-mode indicators, one or more destination port indicators, and/or (long-distance) addresses.

FIELD OF THE INVENTION

The disclosure relates to packet routing, and in particular to routingschemes that enable fast and efficient routing within hyper-connectednetworks of packet processing engines.

BACKGROUND OF THE INVENTION

Information-processing systems that process electronic informationcommonly use electronic storage to store electronic information, digitalprocessors to process the stored electronic information, and busses,networks, or other logic to connect such electronic storage to suchdigital processors. Electronic information is commonly sent ortransmitted by a source (or “origin”) and received by one or moredestinations. For example, the sources may include electronic storage.For example, the destinations may include the digital processors.

Information-processing systems commonly distinguish “write” operationsfrom “read” operations, wherein write operations may be used to storeinformation, e.g. in electronic storage, and wherein read operations maybe used to retrieve information, e.g. for use by a processor. Generally,transfers include electronic information being moved from one componentto another. Write operations and/or read operations may includetransfers.

In information-processing systems having more complicated topologies,hierarchies, and/or architectures, individual read and write operationsmay selectively be associated with one of multiple sources and/ordestinations. In some cases, individual operations may be associatedwith multiple sources and/or destinations. For example, ininformation-processing systems having one or more busses to connectmultiple destinations, one or more appropriate destinations may bedistinguished from one or more inappropriate destinations by variousmeans of disambiguation, such as the use of addresses. Based on theaddress, a read or write operation may be guided to and/or from aparticular source and/or a particular destination.

SUMMARY

One aspect of the disclosure relates to a system and method of routingpackets of information. As used herein, the term “information” mayinclude “electronic information” and/or “digital information.” Therouting system may include one or more packet processing engines, one ormore connections, one or more routers, and/or other components.Individual packet processing engines may include one or more ports.Individual routers may include one or more ports. Connections mayinclude physical, direct, and/or point-to-point connections, for examplebetween ports of different components of the routing system.

The routing system and/or its constituent components may includeelectronic storage to store packets of information, in particularnon-transitive electronic storage, for example one or more memory banks.As used herein, the term “memory bank” may refer to RAM, SRAM, DRAM,eDRAM, SDRAM, volatile memory, non-volatile memory, and/or other typesof electronic memory. The storage capacity of the electronic storage mayrange from a few kilobytes to a few thousand petabytes, and/or anycapacity in-between.

A packet of information may be a predetermined quantity of electronicinformation, albeit potentially a variable quantity, being arranged,organized, and/or formatted in a predetermined manner. As used herein,the terms “packet of information” and “packet” may be usedinterchangeably. Packets may be transferred and/or processedautonomously, e.g. independently from other packets.

Packet-based communication may be used in networks, such as, by way ofexample, the Internet, for various reasons. Decentralized networks mayinclude multiple paths between sources and destinations. Originallybased on queuing theory, packet-switching can be used to providedistributed, scalable, and robust communications, even in the presenceof intermittent connectivity, long transmission delays, variable and/orhigh error rates, and/or other unfavorable operating conditions that mayoccur in networks. Similar conditions may not commonly be associatedwith on-chip communication (or communication within the components of aprinted circuit board, rack, blade, or chassis). For example,communication within a chip or integrated circuit may not includemultiple paths between sources and destination. Such a communicationchip commonly may not suffer from intermittent connectivity, longtransmission delays, variable and/or high error rates, and/or otherunfavorable operating conditions that may occur in networks. For theseand other reasons, on-chip communication (or communication within thecomponents of a printed circuit board, rack, blade, or chassis) mayusually be based on other types of connections/topologies thancommunication within a (distributed) network. On-chip topologies mayinclude one or more of point-to-point topologies, bus topologies, startopologies, tree topologies, and/or other topologies.

Communication within a chip (or communication within the components of aprinted circuit board, rack, blade, or chassis), regardless of topology,may commonly not be based on packets. In the systems described herein,packets of information may be a convenient quantity and/or format forinformation processing purposes, in particular for neural processing. Byvirtue of standardizing and/or matching the units of information usedfor the purposes of storage and/or transfer with the units ofinformation used for the purpose of information processing, i.e.packets, the systems as described herein may be more efficient, simple,flexible, scalable, and/or otherwise preferred over similar systems thatsuffer from a proliferation of different types of connections, differentprotocols, different interfaces, different formats for communications,different units of information, and/or the problems in conversions,design, and/or verification associated such a proliferation. As usedherein, the term “processing” for a packet may be referred to as“consuming” a packet. Packets may not be processed until they havereached their destination.

Individual packets of information may include a packet header. Packetsand/or packet headers may include information and/or sets of values. Theinformation and/or sets of values may include one or more of fields,operands, operator codes, address-mode indicators, source addresses,destination addresses, destination port indicators, and/or otherinformation or values. Individual packets of information may include apacket payload, which may include a variable quantity of electronicinformation. In some implementations, packets may be in accordance witha proprietary protocol. Packets may be referred to as flit packets.Individual packets may range between a minimum bit size and a maximumbit size. The minimum bit size may be 32 bits, 64 bits, 128 bits, 256bits, and/or another suitable minimum bit size. The maximum bit size maybe 512 bits, 1024 bits, 2048 bits, 4096 bits, 8192 bits, and/or anothersuitable maximum bit size. For example, in some implementations, packetsmay range between 64 bits and 2048 bits.

A packet header may include, by way of non-limiting example, anaddress-mode indicator, one or more destination port indicators, and/orone or more addresses. An address-mode indicator may indicate which modeof operation is to be used to route a particular packet. Routing modesand/or routing schemes may include port-by-port routing, (relative orabsolute) address-based routing, and/or other types of routing.Destination port indicators may indicate a port as a destination for aparticular packet. Address-based routing and port-by-port routing mayencode information in the same fields and/or bits within a packetheader. Using the same fields and/or bits within a packet header tosupport multiple modes of routing may be referred to as hybrid routing.The address-mode indicator may be used to distinguish the proper routingmode and/or routing scheme for a particular packet.

Packet processing engines may be configured to generate, receive,transmit, and/or process packets. Packet processing engines may beconfigured to route incoming packets to other packet processing enginesand/or destinations as appropriate. In some embodiments, generation ofone or more output packets may be responsive to receiving one or morepackets. Output packets may be generated by processing one or morereceived packets. Output packets may have similar characteristics and/orformatting as the packets described elsewhere herein. For example,output packets may include an output packet header, an output packetpayload, etc. Packet processing engines may analyze and/or inspect apacket of information to determine whether to transmit and/or to processit. Packet processing engines may be configured to route packets. Forexample, a packet processing engine may receive a packet, determinethrough which port to transmit the packet, and transmit the packetthrough the determined port to a (possibly intermediate) destination.For example, a packet processing engine may receive a packet, determinethat the packet has reached its destination, and process and/or consumethe packet.

Routers may be configured to receive and/or transmit packets ofinformation. Routers may include one or more address tables. Routers maybe configured to determine destinations for packets based on one or moreaddress tables and/or information in the packet. For example, adestination may be determined based on an address in a packet header.Routers may be configured to support address resolution of addresses inpacket headers. In some implementations, a destination may be determinedbased on one or more comparisons between entries in an address table andan address included in a packet.

These and other objects, features, and characteristics of the presentinvention, as well as the methods of operation and functions of therelated elements of structure and the combination of parts and economiesof manufacture, will become more apparent upon consideration of thefollowing description and the appended claims with reference to theaccompanying drawings, all of which form a part of this specification,wherein like reference numerals designate corresponding parts in thevarious figures. It is to be expressly understood, however, that thedrawings are for the purpose of illustration and description only andare not intended as a definition of the limits of the invention. As usedin the specification and in the claims, the singular form of “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a routing system in accordance with one or moreembodiments.

FIG. 2 illustrates a routing system in accordance with one or moreembodiments.

FIGS. 3-5 illustrate methods to processing packets of information usingan on-chip processing system in accordance with one or more embodiments.

DETAILED DESCRIPTION

FIG. 1 illustrates a routing system 100. Routing system 100 mayinterchangeably be referred to as system 100 or information-processingsystem 100. System 100 may include one or more packet processing engines110, one or more connections 111, one or more routers 120 (not shown inFIG. 1), electronic storage (not shown in FIG. 1), one or more externalinterfaces 121 (not shown in FIG. 1), and/or other components. In someimplementations, individual packet processing engines may be implementedin a single chip or integrated circuit. In some implementations, system100 may be implemented in a single chip or integrated circuit. In someimplementations, system 100 may be implemented in a single rack, blade,and/or chassis.

As depicted in FIG. 1, system 100 may include multiple individual packetprocessing engines, including one or more of a packet processing engine110 a, a packet processing engine 110 b, a packet processing engine 110c, a packet processing engine 110 d, a packet processing engine 110 e,and/or other packet processing engines. Individual packet processingengines may include one or more ports configured to transmit and/orreceive information. For example, as depicted in FIG. 1, a packetprocessing engine 110 may include 8 ports (labeled e.g. from 0 to 7). Insome implementations, packet processing engines may include anywherefrom 2 to 32 ports. In some implementations, ports may be labeled from 1onwards, e.g. in case port value zero is used to indicate that a packethas reached its destination and may thus be processed and/or consumed.In some implementations, if packet processing engines include moreports, e.g. between 16 and 32 ports, destination port indicators wouldneed to use a corresponding increased bit-width to distinguish betweenports (and the value that indicates a packet has reached itsdestination).

Connections may include physical, direct, and/or point-to-pointconnections, for example between ports of different components of system100. System 100 may include a set of connections 111, including one ormore of a connection 111 a, a connection 111 b, a connection 111 c, aconnection 111 d, a connection 111 e, a connection 111 f, a connection111 g, and/or other connections. For example, as depicted in FIG. 1,connection 111 a connects port 2 of packet processing engine 110 a toport 5 of packet processing engine 110 b. For example, as depicted inFIG. 1, connection 111 b connects port 3 of packet processing engine 110a to port 7 of packet processing engine 110 d. Connections may include adata bus having a width of 32 bits, 64 bits, 128 bits, and/or anothersuitable width for a data bus.

Packet processing engines may have as many connections as ports, e.g.,in some implementations, 8 ports. System 100 may be referred to asincluding a hyper-connected network of packet processing engines. Insome implementations, system 100 may be more sparsely connected, e.g.such that some packet processing engines have fewer connections thanports. System 100 may typically include more than 8 packet processingengines, e.g. 16, 32, 64, 128, 192, and/or another suitable number ofpacket processing engines. If system 100 includes more packet processingengines than the number of ports for an individual packet processingengine (or more than this number plus one), it necessarily means not allpacket processing engines are directly connected to all other packetprocessing engines. In such a system, packets may be routed via one ormore intermediate packet processing engines prior to arriving at theintended destination. In some implementations, multiple systems that arethe same as or similar to system 100 may operate in combination. In sucha combined system of systems, packets may be routed between a packetprocessing engine of a first system 100 and a packet processing engineof a second system 100.

In some implementations, packet processing engine 110 may include one ormore clusters that are the same as or similar to the system for neuralprocessing (e.g. “system 200”, also referred to as “group 200” andincluding multiple neural processing engines 220) described in U.S.patent application Ser. No. 13/560,890, filed Jul. 27, 2012, andentitled “NEURAL PROCESSING ENGINE AND ARCHITECTURE USING THE SAME”,which is hereby incorporated by reference in its entirety into thepresent disclosure. This application may be referred to as “the '890application” herein. For example, an individual packet processing engine110 may include 8 such clusters (“system 200” in the '890 application)of 32 neural processing engines each (e.g. “neural processing engine220” in the '890 application), or, in other words, 256 neural processingengines per individual packet processing engine. Note that thesespecific pluralities are exemplary and not intended to be limiting inany way.

In some implementations, packet processing engine 110 may include one ormore components that are the same as or similar to the components of theon-chip processing system (e.g. “system 100”) described in U.S. patentapplication Ser. No. 13/705,999, filed Dec. 5, 2012, and entitled “SMARTMEMORY”, which is hereby incorporated by reference in its entirety intothe present disclosure. This application may be referred to as “the '999application” herein.

In some implementations, packet processing engine 110 may be included ina system that may operate in conjunction with a processing system thatis the same as or similar to the on-chip processing system (e.g. “system100”) described in U.S. patent application Ser. No. 13/749,558, filedJan. 24, 2013, and entitled “I/O DATA INTERFACE FOR PACKET PROCESSORS”,which is hereby incorporated by reference in its entirety into thepresent disclosure. This application may be referred to as “the '558application” herein.

System 100 may be configured to store, transfer, and/or process packetsof information. As used herein, packets of information may includeinformation that comprises bits (e.g. a single one or zero) and/or bytes(e.g. eight bits) of information. It is noted that this disclosure isnot limited to binary logic or binary information, even though theexamples herein may assume so.

A packet of information may be a predetermined quantity of electronicinformation, albeit potentially a variable quantity, being arranged,organized, and/or formatted in a predetermined manner. Packets may betransferred and/or processed autonomously, e.g. independently from otherpackets. Individual packets of information may include a packet header.Packets and/or packet headers may include information and/or sets ofvalues. The information and/or sets of values may include one or more offields, operands, operator codes, address-mode indicators, sourceaddresses, destination addresses, destination port indicators, and/orother information or values. A field and/or operator code may includeone or more bits of information that specifies and/or may be used toselect one or more operations to be performed, e.g. on the packetpayload.

Packet headers may adhere to one or more predetermined formats forarranging and/or ordering one or more fields and/or one or more operatorcodes. For example, the size of the packet header may be a fixed numberof bits or bytes. Alternatively, and/or simultaneously, the size of apacket header may be a variable number of bits or bytes, though theparticular size may be indicated in some cases by a field within thepacket header. The size of the packet payload may be a fixed number ofbits or bytes. Alternatively, and/or simultaneously, the size of apacket payload may be a variable number of bits or bytes, though theparticular size may be indicated in some cases by a field within thepacket header.

A packet header may include, by way of non-limiting example, anaddress-mode indicator, one or more destination port indicators, and/orone or more addresses. An address-mode indicator may indicate which modeof operation is to be used to route a particular packet. Routing modesand/or routing schemes may include port-by-port routing, (relative orabsolute) address-based routing, and/or other types of routing.Destination port indicators may indicate a port as a destination for aparticular packet. As used in this context, the destination may be thefinal destination of a particular packet or the immediate destinationthat is intended to be reached from the current packet processing enginethat is inspecting the particular packet. Address-based routing andport-by-port routing may encode information in the same fields and/orbits within a packet header. The address-mode indicator may be used todistinguish the proper routing mode and/or routing scheme for aparticular packet. As depicted in FIG. 1, a packet 200 may include aheader 201, a payload 202, an address-mode indicator 203, an address204, one or more destination port indicators 205, and/or otherinformation. The one or more destination port indicators may include afirst destination port indicator 205 a, a second destination portindicator 205 b, and/or other destination port indicators. In someimplementations, address 204 may be mutually exclusive with the one ormore destination port indicators 205. For example, this information mayuse the same bits in header 201. The one or more destination portindicators may be used to indicate the immediate destination that isintended to be reached from the current packet processing engine that isinspecting the particular packet. Some information in header 201 may beinterpreted to indicate whether the particular packet has reached itsfinal destination, e.g. a packet processing engine intended to performfinal processing on the particular packet. In some implementations, suchinformation may be encoded in one or more (or all) destination portindicators 205.

Packet processing engines 110 may be configured to generate, receive,transmit, and/or process packets. In some embodiments, generation of oneor more output packets may be responsive to receiving one or morepackets. Output packets may be generated by processing one or morereceived packets. Output packets may have similar characteristics and/orformatting as the packets described elsewhere herein. For example,output packets may include an output packet header, an output packetpayload, etc. Packet processing engines may analyze and/or inspect apacket of information to determine whether to transmit and/or to processit.

Packet processing engines 110 may be configured to route packets. Forexample, a packet processing engine may receive a packet, determinethrough which port to transmit the packet, and transmit the packetthrough the determined port to an intermediate or final destination.Packet processing engine 110 may be configured to use one or morerouting modes to route packets. Exemplary routing modes may includeport-by-port routing, address-based routing, and/or other routing modes.

For example, in port-by-port routing, a particular packet processingengine 110 may be configured to determine whether an incoming packet isintended to be processed by that particular packet processing engine or,alternatively, where to route the incoming packet. Port-by-port routingmay be analogous to turn-by-turn directions to reach a destination.Packets may originate at a packet source. Packet sources may includeindividual packet processing engines 110, electronic storage, and/orother sources of packets. For example, a packet processing engine maycreate and/or generate a packet, which subsequently may need to berouted to its destination. For a packet processing engine, the immediatedestination of a packet may be selected from a limited set ofalternatives. For example, the destination may be selected from one ofthe ports of the particular packet processing engine 110.

To illustrate port-by-port routing, assume that packet processing engine110 a receives a packet 200 that includes, in header 201, at least onedestination port indicator 205 a. Assume that the value of destinationport indicator 205 a is 2. Assume that packet processing engine 110 a isincluded in system 100 as depicted in FIG. 1. Assume that a valuebetween 0 and 7 for destination port indicator 205 a indicates that thedestination of packet 200 is the packet processing engine connected tothe port of packet processing engine 110 a that matches the value ofdestination port indicator 205 a. Assume that any other value fordestination port indicator 205 a indicates that the current packetprocessing engine 110, here packet processing engine 110 a, is thedestination of packet 200. Packet processing engine 110 a may beconfigured to determine, by inspecting destination port indicator 205 a,whether packet processing engine 110 a is the destination of packet 200or not. In this example, packet processing engine 110 a is not thedestination of packet 200. Subsequently, packet processing engine 110 amay be configured to determine, by inspecting destination port indicator205 a, which of the ports of packet processing engine 110 a is intendedas destination for transmission of packet 200. In this example, theintended port as destination for packet 200 is port 2. As depicted inFIG. 1, port 2 of packet processing engine 110 a is connected, viaconnection 111 a, to packet processing engine 110 b.

Subsequently, packet processing engine 110 a may be configured tomodify, for example by bit-shifting the one or more destination portindicators 205 in the appropriate field of header 201, one or moredestination port indicators 205. Destination port indicators 205 may bemodified according to a predetermined standard operation on one or moreparticular fields of header 201. In particular, the value of destinationport indicator 205 a may be modified to be not in the range between 0and 7. Subsequently, packet processing engine 110 a may be configured totransmit the modified packet 200 via the indicated port 2, and thus viaconnection 111 a, to packet processing engine 110 b. Upon receivingmodified packet 200, packet processing engine 110 b may be configured todetermine whether the one or more destination port indicators 205indicate that the destination of the received modified packet 200 is thecurrent packet processing engine, here packet processing engine 110 b.In particular, the value of destination port indicator 205 a may nowconfirm that packet 200 has reached its destination. Packet processingengine 110 b may be configured to process packet 200 in a manner similarto the processing described as being performed by the system for neuralprocessing in the '890 application. The values of any destination portindicators, the interpretation of those values, the number of ports perpacket processing engine, the manner in which some information of header200 is modified, and/or the manner in which the contents of header 201is used and/or interpreted to indicate that the destination for packet200 is reached are intended to be exemplary and not limiting in any way.For example, a separate field in header 201 could be toggled to indicatewhether the next receiving packet processing engine 110 within system100 is intended as the destination.

The preceding example of port-by-port routing in system 100 describesthe use of one intermediate packet processing engine 110, here packetprocessing engine 110 a. The number of intermediate packet processingengines in the transfer of a packet to its final destination is notintended to be limited by this example. For another port-by-port routingexample, assume that, in system 100 as depicted in FIG. 1, packetprocessing engine 110 d receives a packet 200 that is intended to reach,as final destination, packet processing engine 110 e. No directconnection may be available to accomplish such a transfer. Assume thateach of three destination port indicators 205 in header 201 is encodedusing 4 bits that are interpreted in a manner similar to theinterpretation of the preceding port-by-port routing example. The valueof the three destination port indicators 205 is represented by a tuple[x,y,z] for destination port indicators 205 a, 205 b, and 205 c,respectively, wherein x, y, and z each have a value between 0 and 15.Destination port indicator 205 c may be referred to as the bottomdestination port indicator. Accordingly, such a tuple may be encodedusing 12 bits. Note that these 12 bits potentially allow routing toreach 8*8*8=512 destinations. A tuple of 24 bits potentially allowrouting to reach 8⁶=262,144 destinations.

At the start of routing packet 200, its tuple may have value [15, 7, 7].Packet processing engine 110 d may be configured to determine whetherthe bottom destination port indicator indicates that packet 200 hasreached its destination. The value 7 indicates the packet has notreached its destination yet. Instead, the immediate destination packetprocessing engine can be reached via port 7, and thus connection 111 b,of packet processing engine 110 d, which is connected to packetprocessing engine 110 a. Prior to transmission, packet processing engine110 d modifies the tuple by right-shifting its 12 bits by 4bit-positions (and inserting 1 s from the left to indicate no value from0 to 7). Accordingly, the tuple now has value [15, 15, 7] when packet200 is received by packet processing engine 110 a.

Packet processing engine 110 a may be configured to determine whetherthe bottom destination port indicator indicates that packet 200 hasreached its destination. The value 7 indicates the packet has notreached its destination yet. Instead, the immediate destination packetprocessing engine can be reached via port 7, and thus connection 111 g,of packet processing engine 110 a, which is connected to packetprocessing engine 110 e. Prior to transmission, packet processing engine110 a modifies the tuple by right-shifting its 12 bits by 4bit-positions (and inserting 1 s from the left to indicate no value from0 to 7). Accordingly, the tuple now has value [15, 15, 15] when packet200 is received by packet processing engine 110 e. Upon receivingmodified packet 200, packet processing engine 110 e may be configured todetermine whether the one or more destination port indicators 205indicate that the destination of the received modified packet 200 is thecurrent packet processing engine, here packet processing engine 110 e.In particular, the value of destination port indicator 205 c may nowconfirm that packet 200 has reached its destination. Packet processingengine 110 e may be configured to process packet 200.

Note that the manner in which destination port indicators are modifiedcorresponds to the manner in which destination port indicators indicatethat a packet has reached its destination. For example, if a destinationport indicator value of zero, i.e. “0000” on destination port indicator205 c, indicates that this packet has reached its destination, then theappropriate modification to a tuple of multiple destination port headersduring routing of such packets would be to right-shift by 4bit-positions and insert four zeroes from the left (e.g. from the mostsignificant bit in this field). By way of illustration, a tuple maystart, at the source of a particular packet, with binary value [“0100”,“0010”, “0101”, “0001”] (or [4, 2, 5, 1]). This packet will then betransmitted, via port “0001” (or 1) to an intermediate packet processingengine, which will receive a modified packet having a tuple with binaryvalue [“0000”, “0100”, “0010”, “0101”] (or [0, 4, 2, 5]). This packetwill then be transmitted, via port “0101” (or 5) to the nextintermediate packet processing engine, which will receive the modifiedpacket having a tuple with binary value [“0000”, “0000”, “0100”, “0010”](or [0, 0, 4, 2]). This packet will then be transmitted, via port “0010”(or 2) to the next intermediate packet processing engine, which willreceive the modified packet having a tuple with binary value [“0000”,“0000”, “0000”, “0100”] (or [0, 0, 0, 4]). This packet will then betransmitted, via port “0100” (or 4) to the next packet processingengine, which will receive the modified packet having a tuple withbinary value [“0000”, “0000”, “0000”, “0000”] (or [0, 0, 0, 0]). At thispoint the packet has reached its destination (e.g. the destinationpacket processing engine), and may thus be processed and/or consumed.

It should be noted that return routing may be unrelated to routing aspreviously described. In other words, while a particular tuple may guidea packet from one packet processing engine to another, the reverserouting may be different. For example, while tuple [15, 7, 7] guides apacket from packet processing engine 110 d to 110 e, the reverse routingwould be accomplished using, e.g., tuple [15, 3, 5].

If, for any reason, packet processing engine 110 a is (deemed to be)unable to perform routing activities with sufficient performance (e.g.speed and/or throughput), system 100 may adapt to find an alternativeroute to the destination of packet 200. For example, a packet may berouted from packet processing engine 110 d to 110 e via intermediatepacket processing engines 110 c and 110 b by using tuple [7, 7, 4] andthus via connections 111 e, 111 c, and 111 f in sequence. The reverserouting would be accomplished using, e.g., tuple [1, 4, 2]. In someimplementations, problems with routing through, e.g., packet processingengine 110 a may occur and be determined dynamically during use ofsystem 100. For example, a particular packet processing engine maybecome a bottleneck for system performance if too many packet (e.g. anunbalanced load) are routed through the same packet processing engine.

If, for any reason, system 100 would need to be replaced with and/orduplicated by a new system, port-by-port routing as described hereinwould operate in the same manner, without a need for re-programmingsoftware and/or hardware that governs the routing. By virtue of thedisclosure described herein, addressing within system 100 (and, inparticular, software for system 100) may be highly portable,relocatable, and/or otherwise flexible. For example, defragmentingmemory by moving processes and/or programs elsewhere within memory maybe supported with ease. Port-by-port routing may provide flexibility inthe layout of a chip, board, rack, blade, and/or chassis by virtue ofsupporting more than one route to most, if not all, destinations.

System 100 may include one or more routers 120. For example, FIG. 2illustrates a routing system 100 that includes a router 120. Router 120may be configured to receive and/or transmit packets of information.Router 120 may support one or more modes of operation to route aparticular packet. Routing modes and/or routing schemes may includeport-by-port routing, (relative or absolute) address-based routing,and/or other types of routing. Packet headers may include anaddress-mode indicator to indicate which mode of operation is to be usedto route a particular packet.

In some implementations, system 100 may use port-by-port routing in casea destination is within system 100, and address-based routing in case adestination is external to system 100. External destinations may bereached via router 120. For example, router 120 may include one or moreconnections to external interface 121. Router 120 may be configured toprovide communication to off-chip systems, device, modules, and/orcomponents. Router 120 may be configured to provide a serial link,including but not limited to a high-speed serial (HSS) link. In someembodiments, router 120 may be configured to provide the physical layerof the Open Systems Interconnect (OSI) model, also referred to as PHY.In some embodiments, router 120 may be configured to provideerror-detection, error-correction, encryption, and/or other supportfunctions commonly used when digital systems, devices, modules, and/orcomponents interconnect and/or communicate. By way of non-limitingexample, router 120 may be configured to support a cyclic redundancycheck (CRC) on information and/or information being transferred.

By virtue of having a dedicated port and connection to router 120,packet processing engines may be configured to determine, e.g. byinspecting the address-mode indicator in the header of a packet, whetherto transmit a packet to router 120. In other words, individual packetprocessing engines may not need to support address-based routing, otherthan to transmit packets to router 120 for address resolution.

In some implementations, after inspecting the address-mode indicator inthe header of a packet, a packet processing engine may be configured toresolve to which port to send the packet. Such address resolution may beimplemented using a (look-up) table, which may need merely 1 entry. Forexample, different packet processing engines may use different ports, ifany, to connect to router 120. In other implementations, packetprocessing engines may use the same port to connect to router 120.

Note that other implementations, including ones that use combinations ofmultiple systems that are similar to or the same as system 100 areenvisioned. Such implementations may employ different rules and/orheuristics to determine which mode of operation is to be used to routefrom a particular source to a particular destination. Individual packetprocessing engines may be configured to transmit packets to the nearestrouter if the address-mode indicator indicates address-based routing. Insome implementations, packet processing engines may not need to supportaddress resolution for address-based routing.

To support port-by-port routing, router 120 may be configured toenumerate one or more ports and/or assign values to one or more portsthat correspond to the values of destination port indicator(s) 205.

Router 120 may include one or more address tables. Router 120 may beconfigured to determine destinations for packets based on one or moreaddress tables and/or information in the packet. For example, adestination may be determined based on an address in a packet header. Insome implementations, a destination may be determined based on one ormore comparisons between entries in an address table and an addressincluded in a packet. Router 120 may be configured to support addressresolution through a look-up operation for one or more address tables.

In some implementations, system 100 may be configured such that all ormost of packet processing engines 110 include a port that has aconnection to router 120. This port may be one of the previouslydescribed (8) ports or it may be a separate and dedicated additionalport. For example, the port for individual packet processing enginesthat connects an individual packet processing engine to router 120 maybe indicated using the same value for destination port indicator 205. Byway of non-limiting example, a value of 0 may indicate the portconnected to router 120, values between 1 and 8 may indicate the portsconnected to other packet processing engines, and values between 9 and15 may indicate that a particular packet has reached its destination.Other encodings to distinguish between different modes of routing,between the port connected to router 120 and other ports, and/or betweenintermediate packet processing engine and the destination packetprocessing engines are envisioned and contemplated within the scope ofthis disclosure.

To illustrate the use of multiple modes of operation for routing apacket, i.e. multiple routing modes, assume that packet processingengine 110 d has received a packet 200, wherein packet 200 is similar tothe packet depicted in FIG. 1. Packet 200 includes, in header 201, anaddress-mode indicator 203. Assume that a value of 0 for address-modeindicator 203 indicates port-by-port routing, and a value of 1 indicatesaddress-based routing. Packet processing engine 110 d may be configuredto determine, e.g. by inspecting address-mode indicator 203, which modeof routing to use for packet 200. In case of port-by-port routing,operation proceeds in a manner similar to the previously describedmanner for other examples. In case of address-based routing, which maybe referred to as long-distance routing in some implementations, packetprocessing engine 110 d may be configured to transmit packet 200, viaconnection 111 h, to router 120. In some implementations, packetprocessing engine 110 d may be configured to use a predetermined port toforward “long distance” packets to. Subsequently, router 120 may beconfigured to determine, through address resolution and/or based onaddress 204 of packet 200, where to route packet 200.

In some implementations, router 120 may be similar to or the same as theon-chip processing system (e.g. “system 100”) described in the '558application.

FIGS. 3-5 illustrate method 300, 400, and 500 of routing packets ofinformation. The operations of methods 300, 400, and 500 presented beloware intended to be illustrative. In some implementations, methods 300,400, and 500 may be accomplished with one or more additional operationsnot described, and/or without one or more of the operations discussed.Additionally, the order in which the operations of methods 300, 400, and500 are illustrated in FIGS. 3-5 and described below is not intended tobe limiting.

In some embodiments, methods 300, 400, and 500 may be implemented in oneor more processing systems (e.g. system 100 as depicted in FIG. 1),processing devices (e.g., a digital processor, an analog processor, adigital circuit designed to process information, an analog circuitdesigned to process information, and/or other mechanisms forelectronically processing information). The one or more processingdevices may include one or more devices executing some or all of theoperations of methods 300, 400, and 500 in response to instructionsstored electronically on an electronic storage medium. The one or moreprocessing devices may include one or more devices configured throughhardware, firmware, and/or software to be specifically designed forexecution of one or more of the operations of methods 300, 400, and 500.

At an operation 302, a first packet of information is received by afirst packet processing engine. Method 300 may be implemented in asystem that includes a set of packet processing engines. Individualpacket processing engines may include multiple ports. The system mayinclude a network of connections between ports of individual packetprocessing engines. The first packet has a destination. The first packetincludes one or more destination port indicators. In some embodiments,operation 302 is performed by a packet processing engine the same as orsimilar to packet processing engine 110 a (shown in FIG. 1 and describedherein).

At an operation 304, it is determined whether the one or moredestination port indicators included in the first packet indicate thatthe receiving engine is the destination of the first packet. In someembodiments, operation 304 is performed by a packet processing enginethe same as or similar to packet processing engine 110 a (shown in FIG.1 and described herein).

At an operation 306, responsive to the determination that the receivingengine is not the destination of the first packet, it is determinedwhether one of the destination port indicators included in the firstpacket indicate the first port of the receiving engine as a target forpacket transmission. In some embodiments, operation 306 is performed bya packet processing engine the same as or similar to packet processingengine 110 a (shown in FIG. 1 and described herein).

At an operation 308, responsive to the determination that one of thedestination port indicators indicates the first port for packettransmission, one or more destination port indicators of the firstpacket is modified. In some embodiments, operation 308 is performed by apacket processing engine the same as or similar to packet processingengine 110 a (shown in FIG. 1 and described herein).

At an operation 310, the modified first packet is transmitted via thefirst port and via a connection between two packet processing engines asindicated. In some embodiments, operation 310 is performed by a packetprocessing engine the same as or similar to packet processing engine 110a (shown in FIG. 1 and described herein).

At an operation 312, the modified packet of information is received by asecond packet processing engine. In some embodiments, operation 312 isperformed by a packet processing engine the same as or similar to packetprocessing engine 110 b (shown in FIG. 1 and described herein).

At an operation 314, it is determined whether the one or moredestination port indicators included in the modified first packetindicate that the second packet processing engine is the destination ofthe modified first packet. In some embodiments, operation 314 isperformed by a packet processing engine the same as or similar to packetprocessing engine 110 b (shown in FIG. 1 and described herein).

At an operation 316, responsive to the determination that the secondpacket processing engine is the destination of the modified firstpacket, the modified first packet is processed. In some embodiments,operation 316 is performed by a packet processing engine the same as orsimilar to packet processing engine 110 b (shown in FIG. 1 and describedherein).

Referring to method 400, at an operation 402, a first packet ofinformation is transmitted by a source packet processing engine. Method400 may be implemented in a system that includes a set of packetprocessing engines, including the source packet processing engine, oneor more intermediate packet processing engines, and a destination packetprocessing engine. The first packet has a destination. The destinationmay be referred to as the destination packet processing engine.Individual packet processing engines may have multiple ports. The systemmay include a network of connections between ports of individual packetprocessing engines. The first packet includes one or more destinationport indicators. In some embodiments, operation 402 is performed by apacket processing engine the same as or similar to packet processingengine 110 a (shown in FIG. 1 and described herein).

At an operation 404, the first packet is received by an individualintermediate packet processing engine. In some embodiments, operation404 is performed by a packet processing engine the same as or similar topacket processing engine 110 b (shown in FIG. 1 and described herein).

At an operation 406, it is determined whether the one or moredestination port indicators included in the first packet indicate thatthe individual intermediate engine is the destination of the firstpacket. In some embodiments, operation 406 is performed by a packetprocessing engine the same as or similar to packet processing engine 110b (shown in FIG. 1 and described herein).

At an operation 408, responsive to the determination that an individualintermediate engine is not the destination of the first packet, it isdetermined which port of the individual engine is indicated by one ofthe destination port indicators as a target for packet transmission. Insome embodiments, operation 408 is performed by a packet processingengine the same as or similar to packet processing engine 110 b (shownin FIG. 1 and described herein).

At an operation 410, responsive to the determination which port of theindividual engine is indicated as the target for packet transmission,one or more destination port indicators of the first packet is modified.In some embodiments, operation 410 is performed by a packet processingengine the same as or similar to packet processing engine 110 b (shownin FIG. 1 and described herein).

At an operation 412, the first packet is transmitted via a port of anindividual intermediate engine as indicated. In some embodiments,operation 412 is performed by a packet processing engine the same as orsimilar to packet processing engine 110 b (shown in FIG. 1 and describedherein).

At an operation 414, it is determined whether the first packet has beentransmitted to a destination packet processing engine. For example, thedestination packet processing engine may be packet processing engine 110d of FIG. 1. If not, operation of method 400 continues at operation 404(for different individual intermediate packet processing engines, e.g.including packet processing engine 110 c) until the first packet hasbeen transmitted to the destination packet processing engine. Else,operation of method 400 continues at operation 416. In some embodiments,operation 414 is performed by a packet processing engine the same as orsimilar to packet processing engine 110 c or 110 d (shown in FIG. 1 anddescribed herein).

At an operation 416, the first packet is received by the destinationpacket processing engine. In some embodiments, operation 416 isperformed by a packet processing engine the same as or similar to packetprocessing engine 110 d (shown in FIG. 1 and described herein).

At an operation 418, it is determined whether the one or moredestination port indicators included in the first packet indicate thatthe receiving packet processing engine is the destination of the firstpacket. In some embodiments, operation 418 is performed by a packetprocessing engine the same as or similar to packet processing engine 110d (shown in FIG. 1 and described herein).

At an operation 420, responsive to the determination that the receivingpacket processing engine is the destination of the first packet, thefirst packet is processed. In some embodiments, operation 420 isperformed by a packet processing engine the same as or similar to packetprocessing engine 110 d (shown in FIG. 1 and described herein).

Referring to method 500, at an operation 502, a first packet ofinformation is received by a first packet processing engine. Method 500may be implemented in a system that includes a router comprising one ormore address tables, a set of packet processing engines, including afirst and second packet processing engine. The first packet has adestination. The destination may be referred to as a destination packetprocessing engine. Individual packet processing engines may havemultiple ports. The system may include a network of connections betweenports of individual packet processing engines. The first packet includesan address-mode indicator. In some embodiments, operation 502 isperformed by a packet processing engine the same as or similar to packetprocessing engine 110 a (shown in FIG. 1 and described herein).

At an operation 504, it is determined whether the address-mode indicatorindicates whether the first packet includes a first address or one ormore destination port indicators. In some embodiments, operation 504 isperformed by a packet processing engine the same as or similar to packetprocessing engine 110 a (shown in FIG. 1 and described herein).

At an operation 506, the first packet is transmitted to the router fortransmission based on the address table of the router, responsive to thedetermination that the first packet includes the first address. In someembodiments, operation 506 is performed by a packet processing enginethe same as or similar to packet processing engine 110 a (shown in FIG.1 and described herein).

At an operation 508, responsive to the determination that the firstpacket includes one or more destination port indicators, it isdetermined whether the one or more destination port indicators includedin the first packet indicate that the first packet processing engine isthe destination of the first packet. In some embodiments, operation 508is performed by a packet processing engine the same as or similar topacket processing engine 110 a (shown in FIG. 1 and described herein).

At an operation 510, responsive to the determination that the firstengine is not the destination of the first packet, it is determinedwhether one of the destination port indicators included in the firstpacket indicates the first port of the first packet processing engine asa target for packet transmission. In some embodiments, operation 510 isperformed by a packet processing engine the same as or similar to packetprocessing engine 110 a (shown in FIG. 1 and described herein).

At an operation 512, responsive to the determination that one of thedestination port indicators indicates the first port of the first packetprocessing engine for packet transmission, one or more destination portindicators of the first packet are modified. In some embodiments,operation 512 is performed by a packet processing engine the same as orsimilar to packet processing engine 110 a (shown in FIG. 1 and describedherein).

At an operation 514, the modified first packet is transmitted via thefirst port as indicated. In some embodiments, operation 514 is performedby a packet processing engine the same as or similar to packetprocessing engine 110 a (shown in FIG. 1 and described herein).

At an operation 516, the modified packet of information is received by asecond packet processing engine. In some embodiments, operation 516 isperformed by a packet processing engine the same as or similar to packetprocessing engine 110 b (shown in FIG. 1 and described herein).

At an operation 518, it is determined whether the one or moredestination port indicators included in the modified first packetindicate that the second packet processing engine is the destination ofthe modified first packet. In some embodiments, operation 518 isperformed by a packet processing engine the same as or similar to packetprocessing engine 110 b (shown in FIG. 1 and described herein).

At an operation 520, responsive to the determination that the secondpacket processing engine is the destination of the modified firstpacket, the modified first packet is processed. In some embodiments,operation 520 is performed by a packet processing engine the same as orsimilar to packet processing engine 110 b (shown in FIG. 1 and describedherein).

Although the invention has been described in detail for the purpose ofillustration based on what is currently considered to be the mostpractical and preferred embodiments, it is to be understood that suchdetail is solely for that purpose and that the invention is not limitedto the disclosed embodiments, but, on the contrary, is intended to covermodifications and equivalent arrangements that are within the spirit andscope of the appended claims. For example, it is to be understood thatthe present invention contemplates that, to the extent possible, one ormore features of any embodiment can be combined with one or morefeatures of any other embodiment.

What is claimed is:
 1. A routing system comprising: a set of packetprocessing engines configured to receive, transmit, and/or processpackets of information, wherein individual ones of the set of packetprocessing engines include multiple ports, wherein an individual packetincludes one or more destination port indicators, wherein the set ofpacket processing engines includes: a first engine including multipleports, and a second engine including multiple ports; a connectionbetween a first port of the first engine and a second port of the secondengine; wherein the first engine is configured to receive a first packetof information, wherein the first packet has a destination, wherein thefirst engine is further configured to determine whether the one or moredestination port indicators included in the first packet indicate thatthe first engine is the destination of the first packet, wherein thefirst engine is further configured to determine whether one of the oneor more destination port indicators of the first packet indicate thefirst port of the first engine as a target for packet transmission,wherein the first engine is further configured to, responsive to thedetermination that one of the one or more destination port indicatorsindicate the first port for packet transmission, modify the one or moredestination port indicators of the first packet and transmit the firstpacket via the first port as indicated, and wherein the one or moredestination port indicators are encoded using multiple bits in a fieldincluded in the first packet, and wherein modification of the one ormore destination port indicators in the first packet is accomplished bybit-shifting the field that includes the one or more destination portindicators, wherein the second engine is configured to receive themodified first packet transmitted by the first engine, wherein thesecond engine is further configured to determine whether the one or moredestination port indicators included in the modified first packetindicate that the second engine is the destination of the first packet,and wherein the second engine is configured to process the modifiedfirst packet responsive to the determination that the one or moredestination port indicators indicate that the second engine is thedestination of the first packet.
 2. The system of claim 1, wherein thefirst engine is configured to receive the first packet of informationfrom an individual one of a set of packet sources, wherein the set ofpacket sources includes one or more packet processing engines and/or oneor more electronic memories.
 3. The system of claim 1, wherein thedestination of the first packet is an individual one of a set of packetdestinations, wherein the set of packet destinations includes one ormore packet processing engines and/or one or more electronic memories.4. The system of claim 1, wherein the first port of the first engine isconfigured to form a point-to-point connection with the second port ofthe second engine.
 5. The system of claim 1, wherein packets includepacket headers, and wherein packet headers include the one or moredestination port indicators.
 6. The system of claim 1, wherein anindividual one of the set of packet processing engines comprises a setof neural processing engines, wherein individual neural processingengines comprise: non-transitive electronic storage configured to storeinstruction code implementing one or more operations; a register fileconfigured to electronically and non-transitively store information,wherein the register file comprises: a first packet space into whichpackets have been individually transmitted, wherein individual packetsfurther include one or more operands, and a second packet space fromwhich output packets are to be individually transmitted, the outputpackets including output values; a micro-sequencer configured todetermine, responsive to an individual packet having been transmittedinto the first packet space, one or more operations to be executed basedon one or more operator codes included in the individual packet; and anarithmetic logic unit configured to perform the one or more determinedoperations on the one or more operands included in the individual packetsuch that one or more output values are generated by executing thestored instruction code that implements the one or more determinedoperations, wherein the micro-sequencer is further configured toassemble the one or more output values generated by the arithmetic logicunit as an output packet in the second packet space.
 7. A method toroute packets of information, the method being implemented in a systemthat includes a set of packet processing engines including a firstengine comprising multiple ports and a second engine comprising multipleports, and a connection between a first port of the first engine and asecond port of the second engine, the method comprising: receiving, bythe first engine, a first packet of information, the first packet havinga destination, wherein the first packet includes one or more destinationport indicators; determining whether the one or more destination portindicators included in the first packet indicate that the first engineis the destination of the first packet; determining, responsive to thedetermination that the first engine is not the destination of the firstpacket, whether one of the one or more destination port indicatorsincluded in the first packet indicates the first port of the firstengine as a target for packet transmission; modifying, responsive to thedetermination that one of the one or more destination port indicatorsindicates the first port for packet transmission, the one or moredestination port indicators of the first packet, wherein the one or moredestination port indicators comprise three port indicator values forminga tuple, and modifying the one or more destination port indicators inthe first packet is accomplished by bit-shifting the tuple in adirection to shift off, in a first end of the tuple, one port indicatorvalue for a port already gone through by the packet and add zeros to thetuple in a second end of the tuple; transmitting the modified firstpacket via the first port as indicated; receiving, by the second engine,the modified packet of information; determining whether the one or moredestination port indicators included in the modified first packetindicate that the second engine is the destination of the modified firstpacket; and processing, responsive to the determination that the secondengine is the destination of the modified first packet, the modifiedfirst packet.
 8. A method to route packets of information, the methodbeing implemented in a system that includes a set of packet processingengines including a source engine, one or more intermediate engines, anda destination engine, wherein individual packet processing engines havemultiple ports, and a network of connections between ports, the methodcomprising: transmitting, by the source engine, a first packet ofinformation, the first packet having a destination, wherein the firstpacket includes one or more destination port indicators; receiving, byan individual intermediate engine, the first packet; determining whetherthe one or more destination port indicators included in the first packetindicate that the individual intermediate engine is the destination ofthe first packet; determining, responsive to the determination that theindividual intermediate engine is not the destination of the firstpacket, which port of the individual engine is indicated by the one ormore of the destination port indicators as a target for packettransmission; modifying, responsive to the determination which port ofthe individual engine is indicated as the target for packettransmission, one or more destination port indicators of the firstpacket, wherein the one or more destination port indicators are encodedusing multiple bits in a field included in the first packet, and whereinmodifying the one or more destination port indicators in the firstpacket is accomplished by bit-shifting the field that includes the oneor more destination port indicators; transmitting the first packet via aport of the individual intermediate engine as indicated; iterating overreceiving the first packet by an individual intermediate engine throughtransmitting the first packet via a port of the individual intermediateengine for different individual intermediate engines until the firstpacket is transmitted to the destination engine; receiving, by thedestination engine, the first packet; determining whether the one ormore destination port indicators included in the first packet indicatethat the destination engine is the destination of the first packet; andprocessing, responsive to the determination that the destination engineis the destination of the first packet, the first packet.
 9. A routingsystem comprising: a router configured to receive and/or transmitpackets of information, wherein the router includes an address table,and wherein the router is configured to determine where to route packetsbased on comparisons between entries in the address table and addressesincluded in packets; a set of packet processing engines configured toreceive, transmit, and/or process packets of information, whereinindividual ones of the set of packet processing engines include multipleports, wherein an individual packet includes an address-mode indicator,wherein the set of packet processing engines includes: a first engineincluding multiple ports, and a second engine including multiple ports;a connection between a first port of the first engine and a second portof the second engine; a connection between the first engine and therouter; wherein the first engine is configured to receive a first packetof information, wherein the first packet includes a first address-modeindicator, wherein the first engine is further configured to determinewhether the first address-mode indicator indicates that the first packetincludes a first address or one or more destination port indicators,wherein the first engine is configured to transmit the first packet tothe router responsive to the determination that the first packetincludes the first address, wherein the first engine is configured todetermine, responsive to the determination that the first packetincludes the one or more destination port indicators, whether one of theone or more destination port indicators of the first packet indicatesthe first port of the first engine as a target for packet transmission,wherein the first engine is further configured to, responsive to thedetermination that one of the one or more destination port indicatorsindicates the first port for packet transmission, modify the one or moredestination port indicators of the first packet and transmit the firstpacket via the first port as indicated, wherein the one or moredestination port indicators comprise three port indicator values forminga tuple, and modifying the one or more destination port indicators inthe first packet is accomplished by bit-shifting the tuple in adirection to shift off, in a first end of the tuple, one port indicatorvalue for a port already gone through by the packet and add zeros to thetuple in a second end of the tuple, wherein the second engine isconfigured to receive the modified first packet transmitted by the firstengine, wherein the second engine is further configured to determinewhether the one or more destination port indicators included in themodified first packet indicate that the second engine is a destinationof the first packet, and wherein the second engine is configured toprocess the modified first packet responsive to the determination thatthe one or more destination port indicators indicate that the secondengine is the destination of the first packet.
 10. A method to routepackets of information, the method being implemented in a system thatincludes a router comprising an address table, a set of packetprocessing engines including a first engine comprising multiple portsand a second engine comprising multiple ports, a connection between afirst port of the first engine and a second port of the second engine,and a connection between the first engine and the router, the methodcomprising: receiving, by the first engine, a first packet ofinformation, the first packet having a destination, wherein the firstpacket includes an address-mode indicator; determining whether theaddress-mode indicator indicates whether the first packet includes afirst address or one or more destination port indicators; transmitting,responsive to the determination that the first packet includes the firstaddress, the first packet to the router for transmission based on theaddress table; determining, responsive to the determination that thefirst packet includes the one or more destination port indicators,whether the one or more destination port indicators included in thefirst packet indicate that the first engine is the destination of thefirst packet; determining, responsive to the determination that thefirst engine is not the destination of the first packet, whether the oneor more of the destination port indicators included in the first packetindicate the first port of the first engine as a target for packettransmission; modifying, responsive to the determination that one of theone or more destination port indicators indicate the first port of thefirst engine for packet transmission, the one or more destination portindicators of the first packet, wherein the one or more destination portindicators are encoded using multiple bits in a field included in thefirst packet, and wherein modifying the one or more destination portindicators in the first packet is accomplished by bit-shifting the fieldthat includes the one or more destination port indicators; transmittingthe modified first packet via the first port as indicated; receiving, bythe second engine, the modified packet of information; determiningwhether the one or more destination port indicators included in themodified first packet indicate that the second engine is the destinationof the modified first packet; and processing, responsive to thedetermination that the second engine is the destination of the modifiedfirst packet, the modified first packet.
 11. The system of claim 1,wherein the field comprises three port indicator values forming a tuple,and modifying the one or more destination port indicators in the firstpacket is accomplished by bit-shifting the tuple in a direction to shiftoff, in a first end of the tuple, one port indicator value for a portalready gone through by the packet and add zeros to the tuple in asecond end of the tuple.
 12. The method of claim 8, wherein the fieldcomprises three port indicator values forming a tuple, and modifying theone or more destination port indicators in the first packet isaccomplished by bit-shifting the tuple in a direction to shift off, in afirst end of the tuple, one port indicator value for a port already gonethrough by the packet and add zeros to the tuple in a second end of thetuple.
 13. The method of claim 10, wherein the field comprises threeport indicator values forming a tuple, and modifying the one or moredestination port indicators in the first packet is accomplished bybit-shifting the tuple in a direction to shift off, in a first end ofthe tuple, one port indicator value for a port already gone through bythe packet and add zeros to the tuple in a second end of the tuple. 14.The method of claim 7, wherein the first engine is configured to receivethe first packet of information from an individual one of a set ofpacket sources, wherein the set of packet sources includes one or morepacket processing engines and/or one or more electronic memories. 15.The method of claim 7, wherein the first packet includes a packet headerand the packet header includes the one or more destination portindicators.
 16. The method of claim 8, wherein the first packet includesa packet header and the packet header includes the one or moredestination port indicators.
 17. The method of claim 8, wherein thefirst packet is transmitted via point-to-point connections between theports.
 18. The system of claim 9, wherein the first engine is configuredto receive the first packet of information from an individual one of aset of packet sources, wherein the set of packet sources includes one ormore packet processing engines and/or one or more electronic memories.19. The system of claim 9, wherein the first packet includes a packetheader and the packet header includes the first address-mode indicatorand the first address or the one or more destination port indicators.20. The method of claim 10, wherein the first engine is configured toreceive the first packet from an individual one of a set of packetsources, wherein the set of packet sources includes one or more packetprocessing engines and/or one or more electronic memories, and the firstpacket includes a packet header and the packet header includes theaddress-mode indicator and the first address or the one or moredestination port indicators.